Usage of A records for aliasing

Khachaturov, Vassilii Vassilii at
Tue Nov 2 17:44:37 UTC 1999

1) CNAME is a pointer to another node. So, there is one extra level of
indirection which falls on some part of the DNS framework anyway when CNAME
is used. It means that not only A is aliased by CNAME.
2) if the other node is not served by the same server process, the overhead
of processing of the original DNS request to retrieve the 2 nodes comes in;
if it's on the same server (and, esp., in the same zone), the server will
have no problems returning both RRs (the CNAME and the one pointed to by
that CNAME -- the latter as additional data)
3) avoid cname to cname pointing
4) Design/administration issue -- consider
b	IN A


a	IN A
b	IN A

(imagine both 2 RRs in the same zone and another case when they're in
different zones).

(A) is to say "a stays for the same as the guy who appoints what b is
decides what b is" while (B) says "a stays for this. b stays for that which
occasionally today stays for this, too. a and b are appointed independently
of each other, generally".

This is pretty much the same as in C you can either
typedef int foo;
/* ... things happen */
typedef foo bar;


typedef int foo;
/* ... things happen */
typedef int bar;

with obvious difference.

Hope that clears more mist than it brings in.

Vassilii Khachaturov
Skribu al mi per Esperanto!

-----Original Message-----
From: Chris Buchanan [mailto:csbuchan at]
Sent: Tuesday, November 02, 1999 4:42 AM

A records for aliasing instead of CNAME records, and visa versa?

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